Recently with the widespread of IP telephones using wireless LAN, a softphone by personal computers and the like, users become enable to use more variety of instruments. Accordingly studies have been conducted on so-called ubiquitous computing, in which a computer environment utilized by an individual user and various services given thereby for example, sending and receiving e-mails, reserving and purchasing tickets of various types, are provided by instruments at hand instead of user-specific instruments.
Studies on a ubiquitous communication system also have been conducted. The system applies this ubiquitous computing concept to a communication terminal and combining a plurality of communication terminals such as a mobile telephone, a videophone, a personal computer, a fax machine or the like. Further, in an example of proposed ubiquitous communication systems (see for example Japanese Laid-open Patent Publication No. 2006-270837 and Japanese Laid-open Patent Publication No. 2006-238364), a TV or video camera is used as a transmitter-receiver of video, and a mobile telephone is used as a transmitter-receiver of audio so as to provide functions of a videophone.
In such a ubiquitous communication system, for example, in a case where there are a plurality of communication terminals that can correspond to identical media (video, audio, data and the like) among communication terminals available for a user, a priority that has been set for every communication terminal is referred to so that a communication terminal having the highest priority is determined as the communication terminal to be incorporated into a call.
However, since the priority is set for every communication terminal in the above-mentioned conventional ubiquitous communication system, it is impossible to determine a communication terminal in accordance with a call status of a medium of the communication terminal.
For example, it is assumed that one fixed telephone and two PCs (personal computers) exist. Among these two PCs, one is indicated as PC-1, and the other is indicated as PC-2. In such a case, in determining a communication terminal that can handle a video, it is impossible to select PC-1 when the fixed telephone has an audio call, and to determine PC-2 when the mobile telephone has an audio call. Namely in the above-mentioned conventional ubiquitous communication system, for example when the priority of PC-2 is set higher than that of PC-1, the PC-2 with the higher priority is determined uniformly as the communication terminal that can handle video, even if the fixed telephone has an audio call or even if the mobile telephone has an audio call.